Method for recording information on a multi layer record carrier, and record carrier for use by such method

ABSTRACT

This invention relates to a method for recording information on a multi layer record carrier. The information is recorded on the record carrier according to special filling patterns, such that the record carrier is compatible with the DVD-ROM standard while the time required for closing a session and/or finalizing the disc is reduced. The information is substantially evenly distributed over the layers in blocks of a predefined amount of storage space. The size of these blocks may be flexible and set by the method or read from the record carrier.

The invention relates to a method of recording information on a multilayer record carrier. The invention relates especially to a method ofrecording information on a dual layer recordable DVD disc, such thatthis disc can be played in any DVD-ROM player. The invention furtherrelates to a record carrier for sue by the method according to theinvention, said record carrier comprising at least two informationlayers for storing the information.

After recording information on a recordable DVD record carrier specialactions need to be taken to make the record carrier compatible withexisting playback devices. When a recordable DVD record carrier has tobe made DVD-ROM compliant, such that the recordable DVD record carriercan be played back in any DVD-ROM player, any unwritten areas need to befilled with dummy data according to the DVD-ROM specification. Thisbecause most DVD players cannot cope with a record carrier on which theinformation layer opposite to the information layer holding informationhas no information written on it. This needs to be done when closing asession and/or finalizing a disc.

The total available size for storing data on a dual layer OTP-type(Opposite Track Path) DVD record carrier (recordable, rewritable, aswell as read-only discs) is dependent on the location of the middlezone. When the amount of information to be written is known on forehand,the location of the middle zone can be decided prior to writing.However, when information of a previously unknown size has to be writtenon a dual layer recordable DVD record carrier, the location of themiddle zone should preferably be placed at the maximum allowed position,which results in a maximum storage space. A downside of placing themiddle zone at the maximum allowed position is the amount of time thefilling with dummy data may take.

FIG. 1A shows an example of a worst-case situation where a complete datazone in a layer (Layer 1) has to be filled with dummy data When thecomplete available data zone space on a first layer, such as Layer 0 inFIG. 1A, is written with information, the complete available data zoneon a second layer, such as Layer 1 in FIG. 1A, needs to be filled withdummy data in order to make the recordable disc DVD-ROM compliant. Thiswill take a substantial amount of time.

It is an object of the present invention to provide a method ofarranging the information on a dual layer record carrier such that theamount of time required for making the record carrier compatible withexisting playback devices, especially with DVD-ROM players, will bereduced to a minimum. This without prior knowledge of the amount ofinformation that should be stored.

This object is achieved by providing a method in which a specificfilling pattern is used during the recordings for physicallydistributing the information to be recorded over the information layersof the multi layer record carrier. By using this specific fillingpattern the amount of time required to close/finalize the session ordisc is significantly reduced.

In the method according to the invention recording is switched from afirst information layer of the disc to a second information layer of thedisc each time a predefined amount of storage space is filled. This isschematically depicted in FIG. 2, where paths 1 and 3 indicate writesequences, and paths 2 and 4 indicate layer jumps. A dual layer disc, asis shown in FIGS. 1A, 1B and 2, comprises two information layers,generally referred to as the Layer 0 (L0) and Layer 1 (L1) layer. The L0layer is the information layer located closest to the side of a discwhere a radiation beam, such as a laser beam, used for reading and/orrecording the information enters the disc. The drive initially writes apredefined amount of information (block 1) to layer L0 and then switchesto layer L1 to write the next predefined amount of information (block2). Next, the drive jump back to layer L0 to record a subsequentpredefined amount of information (block 3) behind the previouslyrecorded block 1.

Data to be recorded on a record carrier normally consists of severalfiles. The logical location of each of these files is stored in filesystem tables. Since, for example, a DVD record carrier acts like arandom access memory, the location of the files stored on the recordcarrier is not dependent on the order of these files in the file system.By balancing the amount of information to be written over all layersusing the special filling pattern according to the invention, each ofthe layers will be filled at approximately the same rate.

In an embodiment of the method according to the invention the predefinedamount of information (that is, the block size) is not a fixed amount,but it is an amount that is variably set by the method itself. In apreferred embodiment of the method according to the invention, a valuespecifying this predefined amount of information (that is, the blocksize) is read from the record carrier itself.

The size of the predefined amount of information influences the timerequired for closing a session and/or finalizing a disc. The smaller thesize of the storage space for holding the predefined amount ofinformation, the faster the closing of a session and/or the finalizingof a disc will be. This because the amount of dummy data that needs tobe recorded upon closing and/or finalizing is reduced. However, such asmall size of the storage space will increase the amount of layer jumps,which could negatively affect the recording performance. Moreover,because of the small block sizes, the number of track jumps dumps fromone block of information to another block of information) when readingthe record carrier will increase. Therefore, the optimum size of thestorage space for holding the predefined amount of information isdependent on the type of use of the record carrier (such as, forexample, recording of a continuous video stream or recording of datafiles).

According to the above-described embodiments of the invention, the sizeof the predefined amount of information (that is, the block size) isflexibly set depending on the type of use of the record carrier. Themethod may set the size automatically depending on the amount of data tobe stored, on the way the data to be stored is supplied to the method(streaming or as fragmented blocks), or on the application.Alternatively, a user sets the size of the predefined amount ofinformation manually.

Moreover, this size of the predefined amount of information needs not befixed during the entire use of the record carrier, but according to anembodiment may be changed between recording sessions. For example, afirst recording session may be recorded with a first size of thepredefined amount of information, while a subsequent second recordingsession may be recorded with a second size of the predefined amount ofinformation, the second size being different from the first size. Inthis way, a single record carrier may support different types of uses.

According to a preferred embodiment, the method reads informationregarding the size of the predefined amount of information from therecord carrier itself. This information may be stored on the recordcarrier as a parameter in an area on the record carrier comprisingparameters indicative of the recording process. When the type of use ofthe record carrier is fixed and/or a preferred size of the predefinedamount of information is known beforehand, this information may beprerecorded on the record carrier. Alternatively, the informationregarding the size of the predefined amount of information may berecorded on the record carrier by the method itself. For example, thelast selected size of the predefined amount of information is stored onthe record carrier for re-use in a subsequent recording session.

Embodiments of the invention will now be explained in more detail withreference to the accompanying drawings.

The DVD-ROM format specification describes that an area identified asmiddle zone does not necessary have to be filled with data. When themiddle zone is located at a position prior to its maximum position, lessspace has to be filled with dummy data, as is shown in FIG. 1B. When theamount of information to be written is known on forehand, the locationof the middle zone can be decided prior to writing. However, when thisis not the case, the special filling pattern according to this inventioncan be used to achieve an optimal balance between available user spaceand required closure time.

An embodiment of the method according to the invention is now describedwith reference to FIG. 3 in which the various record carrier states areshown during the various steps of the method, and in which the specialfilling pattern is represented by a sequence of paths:

Step One Starting from an Empty Dual Layer Record Carrier (fig. 3 a):

During recording the record carrier is treated as an open session, so afile system (FS) will not be written until the session is closed;

The middle zone location is placed imaginary at the maximum location,thus providing the maximum amount of storage space.

Step Two (FIG. 3B):

The files (1, 2 and 3) are written on the record carrier. These filesare written sequentially (path a). It is noted that although the filesin FIG. 3 have identical sizes, the actually written files may vary insize.

Step Three (FIG. 3C):

When a predefined amount of storage space is filled, writing ofsubsequent files will stop on Layer 0 and will continue on Layer 1 (pathb). It is noted that this storage space for holding the predefinedamount of information is the maximum amount of space (i.e., a worst-casesituation) that should be padded (that is, written with dummy data) whenclosing a session and/or finalizing a disc. For a recordable DVD discwhere a single layer may hold up to 4.7 Gbyte of data, the size ofstorage space for holding the predefined amount of information shouldpreferably be in the range of 1% (approximately 50 Mbyte) to 10%(approximately 500 Mbyte). The size of the pre-defined recording areashould at least be significantly less than the total amount of storagespace available on a single layer.

The next files (4, 5, 6 and 7 are written sequentially (path c) on Layer1;

Since the dual layer record carrier in this example is of an OTP(Opposite track Path) type, the direction of writing on Layer 0 (path a)is reverse to the direction of writing on Layer 1 (path c).

Step Four (FIG. 3D):

When the storage space for holding the predefined amount of informationon Layer 1 is filled, or the next file to be written (8) does not fit inthe remaining space, writing continues on Layer 0 again (path d);

The next files (8, 9, 10 and 11) are written sequentially on Layer 0(path e) until a predefined location is reached.

Step Five (FIG. 3E):

The writing process will continue on Layer 1 again (path f);

The next files (12, 13, 14 and 15) are sequentially located on Layer 1(path g). Step six (FIG. 3F):

When the current writing operation is finished, future files to berecorded (16) can be located at the next available user space (path h).

In an embodiment of the method according to the invention an alternativespecial filling pattern is used for recording information on a recordcarrier using a Parallel Track Path (PTP) addressing mode. In such arecord carrier using a PTP addressing mode each layer has the addressesranging from the inner diameter of the disc to the outer diameter. Bothlayers have their own lead-in and lead-out areas. There is no middlezone present like in OPT type record carriers. The steps of thisembodiment are now described with reference to FIG. 4:

Reserving the file system space (FS) when the writing starts;

Writing the information on Layer 0 until a predefined position isreached (that is, until the storage space for holding the predefinedamount of information is filled). The files (1, 2 and 3) are writtensequentially (path a);

After a first layer jump (path b) writing the next files (4, 5, 6 and 7)on Layer 1 (path c);

When a predefined position on Layer 1 is reached, writing continuesagain at Layer 0 (path e) after a second layer jump (path d).

The method according to the invention is not only suitable for use withdual layer record carriers, but also for use with multi layer recordcarriers comprising more than two information layers. Such multi layerrecord carriers may use any of the OTP and PTP addressing modes. Thespecial filling patterns for use with such multi layer discs correspondto the ones described above for dual layer discs. FIG. 5 depictsembodiments of the method according to the invention for use with multilayer record carriers consisting of ‘n’ layers, with either the OTP(FIG. 5A) or the PTP (FIG. 5B) addressing mode.

For a multi layer OTP type record carrier (FIG. 5A) it is assumed thatthe address ranges for each layer is opposite in direction with respectto the previous layer. Now, filling takes place from the lowest layer(Layer 0) up until the last layer (Layer n). Subsequent blocks (that is,storage spaces for holding the predefined amount of information) arerecorded on the layers as depicted in FIG. 5A according to the followingspecial filling pattern (that is, sequence of paths):

a→b→c→d→s→t→u→v→e→f→g→h→w→x→y→z.

Each time the topmost layer (Layer n) is reached, the next block ofinformation will be written on the lowest layer (Layer 0) after a jump(path v, respectively, path z).

For a multi layer PTP type record carrier (FIG. 5B) it is assumed thatthe address ranges for each layer is in the same direction as theprevious layer. Again, filling takes place from the lowest layer (Layer0) up until the last layer (Layer n) in a saw-pattern like shape. Nowthe subsequent blocks (that is, storage spaces for holding thepredefined amount of information) are recorded on the layers by aspecial filling pattern as depicted in FIG. 5B:

a→b→c→d→s→t→u→v→e→f→g→h→w→x→y→z.

Again, when the topmost layer (Layer n) is reached, the next file willbe written on the lowest layer (Layer 0) after the jump (path v,respectively, path z).

By applying the special filling patterns according to the invention itis possible to exploit the maximum available user space on a recordcarrier to the fullest, while minimizing the amount of time required toclose/finalize the disc or session. When, for example, a recordable DVDdisc is written using the filling patterns according to the invention,such a DVD disc is fully compatible with the existing DVD-ROM standardand can be read by any standard DVD player, including DVD-ROM players.

FIG. 6 shows a table comparing the best-case and the worst-casesituations of the closing/finalizing time when using either the fillingpattern strategy according to the invention or a conventional sequentialfilling. In the best-case situation no closing/finalizing time isrequired in both situation: for sequential filling the complete dataarea is used and no extra filling time is required for padding (that is,writing the dummy data); when using the special filling patternsaccording to the invention the session/disc will be closed/finalizedafter writing sequence g, and again no padding needs to be performed.However, in the worst-case situation a significant reduction of the timerequired for closing/finalizing is obtained when the method according tothe invention is applied. For conventional sequential filling theclosing/finalizing time equals the time required for recording acomplete layer. When half of the available disc capacity is used (thatis, only one layer is recorded), the other half of the disc capacity(i.e., the other layer) needs to be padded (that is, written with dummydata). Now, when using the special filling patterns according to theinvention, the closing/finalizing time equals only the time required forrecording the storage space for holding the predefined amount ofinformation with dummy data. On Layer 1 an area with the size of thestorage space for holding the predefined amount of information, which issignificantly less than the total recording area on Layer 1, should bepadded in order for the disc to be DVD-ROM compliant. For a recordableDVD disc where a single layer may hold up to 4.7 Gbyte of data, the sizeof the pre-defined recording area should preferably be in the range of50 Mbyte to 500 Mbyte (that is, at least significantly less than thetotal amount of storage space available on a single layer).

1. A method of recording information on a multi layer record carrier,said record carrier comprising at least two information layers forrecording the information, wherein the information to be recorded isdistributed over the at least two layers according to a distributionpattern such that the amount of information stored on the at least twolayers differs between the layers by a predefined amount of informationor less.
 2. Method as claimed in claim 1 wherein the information isrecorded in subsequent blocks, each block for holding the predefinedamount of information, and wherein the distribution pattern is such thattwo subsequent blocks are not recorded on the same information layer. 3.Method according to claim 1, wherein areas holding recorded informationon the at least two layers are superjacent.
 4. Method according to claim1, wherein the predefined amount of information is significantly lessthan the total amount of storage space available on one of the at leasttwo information layers.
 5. Method according to claim 2, wherein themethod comprises an initialization step of setting the size of saidblock for holding the predefined amount of information, and a subsequentrecording step of recording information on said at least two informationlayers such that the information is recorded alternately on said atleast two information layers, the recording step comprising the steps ofrecording information on a layer until the block for holding thepredefined amount of information is filled, and subsequently recordinginformation on a different layer of said at least two informationlayers.
 6. Method according to claim 5, wherein in the initializationstep a value indicative of the size of the block for holding thepredefined amount of information is read from the record carrier, andwherein the size of the block for holding the predefined amount ofinformation is set in dependence on the read value.
 7. Method accordingto claim 6, wherein the method comprises a further step of recording avalue indicative of the set size of the block for holding the predefinedamount of information on the record carrier.
 8. Method according toclaim 5, wherein the size of the block for holding the predefined amountof information is set in dependence on the amount of information to bestored, or on the way the information to be stored is supplied to themethod, or on the type of the application supplying the information. 9.A method of recording information on a multi layer record carrier, saidrecord carrier comprising at least two information layers for storingthe information, wherein the method comprises a first initializationstep of setting the size of a first block for holding the predefinedamount of information, and a subsequent first recording step in a firstrecording session for recording information on said at least twoinformation layers such that the information is recorded alternately onsaid at least two information layers, the first recording stepcomprising the steps of recording information on a layer until the firstblock for holding the predefined amount of information is filled, andsubsequently recording information on a different layer of said at leasttwo information layers, and a second initialization step of setting thesize of a second block for holding the predefined amount of information,and a subsequent second recording step in a second recording session,the second recording step comprising the steps of recording informationon a layer until the second block for holding the predefined amount ofinformation is filled, and subsequently recording information on adifferent layer of said at least two information layers
 10. A recordingdevice for recording information on a multi layer record carrier, saidrecord carrier comprising at least two information layers for recordingthe information, wherein the device is adapted for carrying out a methodas claimed in claim
 1. 11. A multi layer record carrier comprising atleast two information layers for storing information, said recordcarrier comprising a region holding parameter values indicative of arecording process for recording information on the record carrier,characterized in that said region comprises a value indicative of thesize of a block for holding a predefined amount of information, saidvalue indicative of the size of the block for holding the predefinedamount of information used in a method according to claim 6.